Thermal ageing of a supported epoxy-imide adhesive

A supported epoxy-imide adhesive has been aged in air at elevated temperatu res (180-250 degrees C). Evolution of the material has been studied using g ravimetry, optical microscopy, X-ray microanalysis, and viscoelasticimetry. Mass loss was manifest and has been shown to be more significant from adhe sive surfaces exposing fibres (the support) than from those presenting only polymer. Microscopic examination and X-ray microanalysis indicated the for mation of oxidised regions near the exposed surfaces of the polymer. Region s with exposed fibres degraded more rapidly due to facilitated oxygen ingre ss. This surface governed form of degradation seems to be accompanied by bu lk thermolytic ageing, not requiring oxygen, as shown by viscoelasticimetry , indicating a drop in the glass transition temperature, T-g, after ageing. (C) 2000 Elsevier Science Ltd. All rights reserved.